This invention relates to an automotive air cleaner for an internal combustion engine and a filter element therefor.
Significant advances have been made in recent years in controlling the emission of hydrocarbon pollutants from vehicle engines. As a result, a significant proportion of the remaining hydrocarbon emissions from a vehicle engine occur after the vehicle engine has been turned off. While the engine cools down after the ignition has been turned off, some of the fuel remaining in the carburetor boils out through the vehicle air cleaner. In order to reduce the hydrocarbon emissions to the absolute minimum, it is desirable to provide a vehicle air cleaner and filter cartridge therefor which traps the fuel vapors in the air cleaner and prevents their escape into the atmosphere when the vehicle engine is turned off. Of course, it is also necessary that this emission control arrangment not interfere with the normal running operation of the engine. The present invention solves these problems by providing a "trap door" valve mechanism in the inlet snorkel tube connected to the air cleaner. When the vehicle engine is turned off, the trap door valve element is urged into sealing engagement with the valve seat in the snorkel tube, thereby preventing communication of fuel vapors through the snorkel tube into the atmosphere. An improved filter element, which includes a charcoal impregnated pleated paper element in addition to the normal pleated paper filtering element, adsorbs fuel vapors trapped in the air cleaner. When the vehicle engine is to be started, an actuator opens the trap door valve element an incremental amount sufficient to permit sufficient combustion air to enter the engine to allow the engine to start. When the engine starts, air communicating through the snorkel tube reacts against the transverse surface of the trap door valve element, thereby forcing it to assume a new position dependent on the pressure differential formed across the valve element. Accordingly, whenever the engine is operating, the valve element in the snorkel tube is automatically held in an opened position by communication of combustion air through the snorkel tube. Prior art devices general required complicated electrical or vacuum operated actuators to ensure that the valve element remained in an open position. The prior art also provides a charcoal ring which was used in series with the conventional pleated paper filter element, but this charcoal ring was commonly placed downstream of the conventional filter element, which permitted carbon particles to break off from the ring and enter the engine. Furthermore, these rings were not a part of the air cleaner element, so that the vehicle owner was not forced to change the carbon ring at regular intervals, as is necessary to ensure proper vapor adsorption.
Therefore, one advantageous effect of our invention is that the inlet snorkel tube of an engine air cleaner is sealed against the escape of hydrocarbon vapors when the engine is shut off, but is automatically open upon starting of the engine to permit combustion air to reach the carburetor.
Another advantageous effect of our invention is to provide an air cleaner with an improved air filter element which includes an integral vapor adsorbent material which is pleated with the pleated paper element and which is changed when the filter element is changed, and in which charcoal from the vapor adsorbent element is prevented from reaching the engine.